Power line communication (PLC), also called mains communication, power line transmission or power line telecommunication (PLT), broadband power line (BPL), power band or power line networking (PLN) is a term describing several different systems for using power distribution wires for simultaneous distribution of data. A carrier can communicate voice and data by superimposing an analog signal of the standard 50 or 60 Hz alternating current (AC). For indoor applications, PLC equipment can use household electrical power wiring as a transmission medium. This is a technique used e.g. for home networking or in home automation for remote control of lighting and appliances without installation of additional wiring.
In standard PLC systems the signals are transmitted and received in a differential-mode (DM). Differential-mode signaling is a method of transmitting information over pairs of wires. At DM signaling one wire carries signal and the other wire carries the inverse of the signal, so that the sum of the voltages to ground on the two wires is always assumed to be zero. PLC modems therefore inject a DM signal between a neutral line and a phase line of an outlet of the power line network of the household for communication purposes. Another PLC modem can receive such DM signals at another outlet and use the DM signal for controlling an appliance associated with the receiving PLC modem.
At in-house power line grids, there are asymmetric elements between the phase line and the neutral line, like e.g. an open light switch, a current bar and a fuse cabinet, branches etc. At these asymmetric elements, the DM signals injected by PLC modems are converted to common-mode (CM) signals. Multiple input multiple output (MIMO) PLC modems can use different channels, in particular also common-mode signals, in order to enhance the coverage of PLC systems.
Therefore, there is need for an improved device for a determining a common-mode signal in a power line communication network.